This invention relates to measuring power of signals. More particularly, the present invention relates to methods and apparatus for measuring a wide power range of signals by measuring the input signal at both high and intermediate frequency.
Power measuring receivers may be used to measure the power associated with high frequency signals, such as signals found in wireless communication systems. These receivers may measure a finite range of the power associated with the high frequency signal by using, for example, a logarithmic amplifier technique. A power measuring receiver such as a conventional radio frequency (RF) power detector may use multiple gain stages (e.g., amplifiers) and detectors (e.g., signal detectors) to measure the power of the high frequency input signal. However, measurement of power signals in conventional power measuring receivers may be limited by high noise bandwidth in the receiver. At high frequencies, the noise bandwidth may prevent accurate measurement of low power signals. In addition, when these receivers are designed to measure a wide range of power signals, numerous gain stages and detectors may be needed, which can result in high levels of power consumption.
Other power measuring receivers, such as an intermediate frequency power detector, may correct the problem of high noise bandwidth and extensive DC power consumption associated with the conventional power detector. The intermediate power detector may measure the input signal indirectly by converting the frequency of the original input signal (i.e., high frequency signal) to an intermediate frequency signal, which is then provided to detectors for measurement. This receiver may be able to measure the power signal at a relatively low noise bandwidth because noise bandwidth is directly correlated to the frequency (i.e., higher frequency results in more noise). However, the intermediate frequency power detector may not be able to measure high power input signals operating at high frequency (e.g., radio frequency) because the high power saturates the high frequency gain stages. In addition, when low power input signals are measured, the error feed-through associated with the converting circuitry may prevent the power detector from accurately measuring the power. Thus, these limitations can prevent the intermediate power receiver from measuring a wide range of power.
In view of the foregoing, it would be desirable to provide a power measuring receiver that measures input signal power at a wide dynamic power range with high sensitivity.
It would also be desirable to provide a power measuring receiver that measures input signal power at both a high frequency and an intermediate frequency at low noise bandwidth.
It would also be desirable to provide a power measuring receiver that consumes low quantities of DC power.
It is therefore an object of the present invention to provide a power measuring receiver that measures input signal power at a wide dynamic power range with high sensitivity.
It is also an object of the present invention to provide a power measuring receiver that measures input signal power at both a high frequency and an intermediate frequency at low noise bandwidth.
It is also an object of the present invention to provide a power measuring receiver that consumes low quantities of DC power.
In accordance with these and other objects of the invention, methods and apparatus for a power measuring receiver that measures input signal power at a wide power range are provided. The power measuring receiver measures a wide range of input signal power by measuring the same input signal at two different frequencies so that an extended measurable power range is obtained while providing accurate detection of input signal power. The power measuring receiver that measures input signal power at two different frequencies may have, in accordance with the present invention, high frequency measuring circuitry, conversion measuring circuitry, and intermediate frequency measuring circuitry, which work in conjunction with each other to measure the power of the signal at both high frequency and intermediate frequency.
High Frequency measuring circuitry may measure relatively strong input power signals by using, for example, a detector or detectors used in combination with signal altering circuits. Signal altering circuits may be included to change the magnitude of the signal so that the signal can be measured by the detectors. Signal altering circuits may be, for example, gain stage circuitry, attenuation stage circuitry, or any other suitable circuitry. High frequency measuring circuitry may provide the power measuring receiver with the high end of the wide range of measurable power.
Conversion measuring circuitry may down-convert the frequency of the input signal from high frequency to intermediate frequency and measure the power of the reduced frequency signal. Conversion measuring circuitry may measure the reduced frequency signal with a detector or a detector used in combination with signal altering circuits. In addition, the conversion measuring circuitry may set the minimum level of noise bandwidth so that the intermediate frequency measuring circuitry and accurately measure the power of the input signal.
Intermediate frequency measuring circuitry may measure relatively low input power signals using, for example, a detector or a detector used in combination with signal altering circuits. These detectors may be able to accurately measure low power signals because they are measuring power of the signal at intermediate frequency and at a low noise bandwidth. Intermediate frequency measuring circuitry may provide the power measuring receiver with the low end of the wide range of measurable power.
Since power measurement of the input signal may occur at intermediate frequency, this can provide the intermediate frequency measuring circuitry with the ability to measure the input signal at a reduced DC power consumption. The lower frequency of the signal results in less power consumption by detectors, signal altering circuits, or any other suitable circuitry provided with the power measuring receiver.